Hydraulic apparatus and control for a press

ABSTRACT

The disclosure of the present invention relates to the provision of two groups of cooperative piston cylinder assemblies supplied by two different power sources for a press for compacting fragmentalized metal into highly densed blocks. The operation of the two groups of piston cylinder assemblies with reference to the progressively increased resistance offered during the compacting operation, and hence, the corresponding decrease in speed of the press ram is controlled by a pinion drive transducer in combination with a limit switch-speed switch arrangement.

[ June 10, 1975 United States Patent n 1 Kent et al.

IOU/48 IOU/48 [54] HYDRAULIC APPARATUS AND CONTROL 3,138,976 {R'Vobra3,242,533 intriss.............. FOR A PRESS 3,416,433 l2/l968 Gutnikovet al.

[75] Inventors: Francis Joseph Kent, Wallingford',

Seymour E. Steinbrook, Wynnewood, both of Pa.

Primary Examiner-Billy J. Wilhite Attorney, Agent, or Firm-Henry C.Westin; Daniel Patch [73] Assignee: Wean United, Inc., Pittsburgh, Pa.

[22] Filed: June 4, I973 21 Appl, No.: 367,051

provision of two groups of cooperative piston cylinder [52] U.S. 100/48;83/617; IOU/269 R assemblies supplied by two different power sources for[5 1] III- a press for p i g fragmentalized mcla! into highly densedblocks.

[58] Field of Search 72/44], 443, 8; 83/554, The operation of the wegroups 83/617 74; 9l/4l2' 364; 425/135; of piston cylinder assemblieswith reference to the 269 R progressively increased resistance offeredduring the compacting operation, and hence, the corresponding decreasein speed of the press ram is controlled by a 7 Claims, 2 Drawing Figures1,907,083 Meyercord et al........,. /269 R X 3,044,389 Rexford [00/483,08l 6S9 Theobald 83/554 MAIN CONTROL DIRECTIONAL VALVE CONTROLDIRECTIONAL VALVE CYLINDER CONTROL DIRECT IONAL VALVE PATENTEDJUH I 0 msSHEET O UMmJ b I O NwJ 9 n m M RAMS DOWN ON LOW PRESSURE CYLINDERS l4,I8, 20, AND 22 ZERO SPEED RAMS DOWN ON HIGH PRESSURE CYLINDERS 1a, 20,AND 22 L53 4cn 0-4 -il* RAM Down on HIGH PRESSURE CYLINDER l4- 36R 7FIG. 2

1 HYDRAULIC APPARATUS AND CONTROL FOR A PRESS Hydraulic presses arepresently employed in performing work where the press ram or rams have arelatively long working stroke or strokes and wherein the speed of theram or rams during the stroke is substantially reduced due to theincreased resistance offered by the workpiece, for example, due to theincreased density of the workpiece due to its being compressed by theram or rams, in such applications, there is a great need and interest inconserving the power and time to perform the total pressing operation.

It is therefore the object of the present invention to provide amulti-piston cylinder assembly arrangement for a press, in combinationwith a control means for conserving the power required to operate thepiston cylinder assemblies with reference to a change in speed of thepress and the time necessary to perform the total pressing operation interms of an increase in the resistance offered by a workpiece during thepressing operation.

More particularly, the present invention provides a single group ormulti-group of piston cylinder assemblies associated with a working ramof a press and a control means for said piston cylinder assembliesincluding means sensitive to a change in the speed of the ram and ameans for changing the working force of a piston cylinder assembly or anumber of the piston cylinder assemblies of a single group or two ormore groups of cylinder assemblies with reference to the detected changein the speed of the ram.

it is a still further object of the present invention to provide for aworking ram of a press a main piston cylinder assembly and one or moreauxiliary piston cylinder assemblies in combination with a low pressuresystem for said main and auxiliary piston cylinder assemblies, a highpressure system for said main and auxiliary piston cylinder assemblies,a speed measuring means associated with said ram to measure its speedduring its working stroke, a cylinder selector means associated with thespeed measuring means arranged to first effect a connecting of the lowpressure system to one or more of said piston cylinder assemblies, andthen to effect a connecting of the high pressure system to one or moreof said piston cylinder assemblies.

in another object of the present invention the low pressure system takesthe form of a prefill pressure system, the speed measuring meansincludes a transducer and the cylinder selector means includes a limitswitchspeed switch arrangement.

These objects, as well as other novel features and advantages of thepresent invention, will be better appreciated when the followingdescription of one embodiment thereof is read along with theaccompanying drawings of which:

FIG. 1 is a schematic elevational view, partly in section, of ahydraulic press, and particularly, of the piston cylinder assemblyarrangement and hydraulic systems thereof constructed in accordance withthe present in vention,

FIG. 2 is an electrical diagram of part of the speed and power controlsystem for the piston cylinder assembly arrangement shown in FIG. 1.

in referring to FIG. 1 there is shown the upper portion of a pistoncylinder arrangement of a compacting press of which the main crossheadis fragmentally shown connected to the upper portion of a verticallyarranged ram 12 of the press. Other components of the press have notbeen shown since they may follow wellknown designs and a descriptionthereof is not required to understand the present invention. The pistoncylinder assembly arrangement of the press is shown since it forms animportant part of the invention. It consists first of a centrallylocated main piston cylinder assembly 14, the ram 16 of which engagesthe top of the crosshead l0. Outward of the main cylinder assembly 14there are three equally spaced similar auxiliary piston cylinderassemblies 18, 20, and 22, their rams 24 also engaging the upper surfaceof the crosshead l0. Lastly, intermediate the main and auxiliarycylinders there are located a pair of pull back piston cylinderassemblies 25 and 26 for the crosshead 10.

The main piston cylinder assembly 14 and the three auxiliary pistoncylinder assemblies 18, 20 and 22 may be considered in function andoperation as separate groups of cylinders in which the two groups areassociated in common with two different hydraulic power systems, onebeing a low pressure or prefill system and the other a substantiallyhigher pressure system. The main piston cylinder assembly 14 hasassociated with it a prefill valve 30 whereas the auxiliary pistoncylinder assemblies are associated with their own prefill valve 32. Bothof these valves 30 and 32 are connected to a prefill system by standards34 and 36, respectively. The standards communicate with an anti-surgedevice 38 which in turn receives water under a prefill pressure from aprefill vessel, not shown. all in accordance with well-known practice.

The prefill valves 30 and 32, which are similar in construction, operatein accordance with well-known valve technology, have center spools 40actuated by operating stems 42 and high pressure orifices 44 forallowing water under the high pressure to pass into cylinder orifices 46when the spools 40 are moved to the left as one views FIG. 1. To thehigh pressure orifice 44 of the valve 30 there is connected piping 48 ofthe high pressure system, which includes a main control directionalvalve 50. The high pressure water for the valve 32 is received by piping52 from an auxiliary control directional valve 54. A third directionalcontrol valve 56 is shown, this valve by piping 58 communicates with thepull back cylinders 26. The directional valves 50, 54 and 56, accordingto well-known practice receive the high pressure fluid from anaccumulator and pump arrangement, such as several direct flow typepumps, not shown. It may be well to note that the pumps and accumulatorwill have a working pressure capacity of order of 4,500 psi, whereas theprefill supply system has a working pressure of 300 psi. It will beappreciated that while they have not been referred to specifically, thetwo hydraulic systems will include valves, strainers, gauges, etc., thatcustomarily are employed in heavy industrial hydraulic applications.

Turning now to the electrical control provided for the coordinatedoperation of the prefill and high pressure systems, it will be noted inFIG. I that connected to the crosshead 10 of the press there is avertical downwardly extending rack 59 which is engaged by a pinion 60 ofa transducer 62. Also associated with the crosshead 10 are threevertically spaced-apart limit switches, LS LS-2, and LS-3, having theirrollers arranged to be contacted sequentially by a cam attached to theadjacent side of the crosshead 10. Referring now to FIG. 2, theelectrical circuitry of the control includes two power lines 64 and 69connected together by a switch 68 in a line 70 which line also includesa relay lCR. On the right side of the switch 68 a line 72 is connectedto the line 70 which allows current to pass through three secondarylines 74, 76 and 78 arranged in parallel. The line 74 includes the limitswitch LS-l, a zero speed switch contact 80 and a relay 4CR. Line 76includes the limit switch LS-2, a contact of the relay 4CR and a relayZCR which is connected into the line 76 on the opposite sides of thecontact 4CR. Lastly, line 78 includes the limit switch LS-3, a secondcontact of the relay 4CR and a relay 3CR which is connected into theline 78 on opposite sides of the second contact 4CR. Also shown in P10.2 is a speed measuring instrument for establishing the setting for thezero speed switch 80 at which setting the relay 4CR will be operated.

The operation of the above described piston cylinder arrangement willnow be briefly outlined. Let it be assumed that the piston cylinderassemblies 14, 18, 20 and 22 are in the position shown in FIG. 1 whichis the position they assume at the top of the working stroke of thepress and that the spools 40 of the prefill valves 30 and 32 arepositioned to be closed to the high pressure system and opened to theprefill system. In this event the switch 68 is operated to activate therelay lCR. Prior to this, the speed switch 80 will have been set by theinstrument 82 to a predetermined speed setting in order to conservepower and time during the downward travel or working travel of thecrosshead 10 of the press. On the operation of the relay lCR water underthe prefill pressure is admitted to all four piston cylinder assemblies14, 18, 20 and 22 to cause the crosshead l and ram 12 to descend on theworkpiece. The descending crosshead will without too much delay engageand trip the limit switch LS-l to activate the relay 4CR.

As the crosshead continues to descend the limit switch LS-2 is trippedand should the speed of the crosshead have fallen below the speedsetting of the speed switch 80 as measured by the instrument 82 thecontact in line 76 of the relay 4CR will close activating the relay ZCR.This will cause the spool 40 of the prefill valve 32 to shift to openthis valve to the high pressure system and admit high pressure fluid tothe auxiliary piston cylinder assemblies 18, and 22 while the mainpiston cylinder assembly 14 is still under the prefill pressure. Thecontact of the relay 4CR in line 76 will remain closed until the speedof the ram has been increased to above the speed setting of the speedswitch 80 after which it will be opened and the current in line 76 willpass through the contact 2CR which was closed on operation of the relayZCR.

As the crosshead continues to descend under the reestablished optimumrate of speed and power the increased resistance offered by theworkpiece due, for example, to its increased density, will again reducethe speed of the ram 12 and when its speed falls below the setting ofthe speed switch 80 and the crosshead has been lowered to trip the limitswitch LS-3 the contact of the relay 4CR in line 78 is closed toactivate relay 3CR. This will cause the spool 40 of the prefil] valve toshift to close off the prefill system from the main piston cylinderassembly 14 and open this piston cylinder assembly to the high pressuresystem so that all fourbeen again re-established the contact 4CR in line78 will open and the current in line 78 will pass through the contact3CR which was closed on operation of the relay 3CR. The limit switchesLS-l, LS-2 and LS-3 are strategically spaced so as to conserve theavailable power and time, in which once the limit switch LS-3 has beentripped, the ram 12 will be approaching the conclusion of its downwardstroke.

In accordance with the provisions of the patent statutes, we haveexplained the principles and operation of our invention and haveillustrated and described what we consider to represent the bestembodiment thereof.

We claim:

1. In a press having at least a first piston cylinder assembly and agroup of second piston cylinder assemblies for causing a ram of thepress to pass through its working stroke,

a first and a second power source for said piston cylinder assemblies,

means sentitive to a change in the speed of said ram during its workingstroke,,

means for connecting one of said power sources to at least said firstpiston cylinder assembly to commence the working stroke, and

means for selectively connecting said other power source to at least oneof said second piston cylinder assemblies with reference to a detectedchange in the speed of said ram to control the speed of said ram duringits working stroke.

2. In a press having a ram,

a first piston cylinder assembly and at least one second piston cylinderassembly for causing said ram to pass through its working stroke,

a low pressure system for said first and second piston cylinderassemblies,

a high pressure system for said first and second piston cylinderassemblies,

a speed measuring means associated with said ram to measure its speedduring its working stroke, and

a piston cylinder assembly selector means associated with said speedmeasuring means arranged to first effect a connecting of said lowpressure system to at least one of said piston cylinder assemblies, andthen to effect a connecting of said high pressure system to at leastsaid other piston cylinder assembly thereby to control the speed of saidram and offset a reduction in the speed of the ram due to in creasedresistance during its working stroke.

3. In a press having a ram,

a first piston cylinder assembly and several second piston cylinderassemblies for causing said ram to pass through its working stroke.

a low pressure system for said first and second piston cylinderassemblies,

a high pressure system for said first and second piston cylinderassemblies,

a speed measuring means associated with said ram to measure its speedduring its working stroke, and

a piston cylinder assembly selector means associated with said speedmeasuring means including means for first effecting a connecting of saidlow pressure system to all of said piston cylinder assemblies and meansfor then effecting a connecting of said high pressure system to at leastsome of said piston cylinder assemblies.

4. In a press according to claim 3 wherein said low pressure systemtakes the form of a prefill pressure system and wherein said speedmeasuring means includes a transducer means and said piston cylinderassembly selector means includes a limit switch-speed switcharrangement.

5. in a press according to claim 4 wherein said transducer meansincludes a rack displaceable by said ram of said press,

a pinion arranged to mesh with said rack and connected to saidtransducer means.

6. In a press according to claim 4 wherein said selector means includesa series of limit switches arranged in a spaced linear relationship withrespect to the direction of travel of said ram adapted to besequentially engaged by said ram during its working stroke,

said speed switch being associated with said limit switch adapted to befirst engaged by said ram during its working stroke so that when engagedsaid speed switch is operative.

7. in a press according to claim 4 wherein said first piston cylinderassembly comprises a main piston cylinder assembly and said secondpiston cylinder assembly comprising one or more auxiliary pistoncylinder assemblies,

means for associating a first limit switch in a manner to effectoperation of said main and auxiliary piston cylinder assemblies by saidlow pressure,

means for associating a second limit switch with said high pressuresystem in a manner to effect operation of said auxiliary piston cylinderassemblies by said high pressure, and

means for associating a third limit switch with said high pressuresystem in a manner to effect said operation of a main piston cylinderassembly by said high pressure.

1. In a press having at least a first piston cylinder assembly and agroup of second piston cylinder assemblies for causing a ram of thepress to pass through its working stroke, a first and a second powersource for said piston cylinder assemblies, means sentitive to a changein the speed of said ram during its working stroke,, means forconnecting one of said power sources to at least said first pistoncylinder assembly to commence the working stroke, and means forselectively connecting said other power source to at least one of saidsecond piston cylinder assemblies with reference to a detected change inthe speed of said ram to control the speed of said ram during itsworking stroke.
 2. In a press having a ram, a first piston cylinderassembly and at least one second piston cylinder assembly for causingsaid ram to pass through its working stroke, a low pressure system forsaid first and second piston cylinder assemblies, a high pressure systemfor said first and second piston cylinder assemblies, a speed measuringmeans associated with said ram to measure its speed during its workingstroke, and a piston cylinder assembly selector means associated withsaid speed measuring means arranged to first effect a connecting of saidlow pressure system to at least one of said piston cylinder assemblies,and then to effect a connecting of said high pressure system to at leastsaid other piston cylinder assembly thereby to control the speed of saidram and offset a reduction in the speed of the ram due to increasedresistance during its working stroke.
 3. In a press having a ram, afirst piston cylinder assembly and several second piston cylinderassemblies for causing said ram to pass through its working stroke, alow pressure system for said first and second piston cylinderassemblies, a high pressure system for said first and second pistoncylinder assemblies, a speed measuring means associated with said ram tomeasure its speed during its working stroke, and a piston cylinderassembly selector means associated with said speed measuring meansincluding means for first effecting a connecting of said low pressuresystem to all of said piston cylinder assemblies and means for theneffecting a connecting of said high pressure system to at least some ofsaid piston cylinder assemblies.
 4. In a press according to claim 3wherein said low pressure system takes the form of a prefill pressuresystem and wherein said speed measuring means includes a transducermeans and said piston cylinder assembly selector means includes a limitswitch-speed switch arrangement.
 5. In a press according to claim 4wherein said transducer means includes a rack displaceable by said ramof said press, a pinion arranged to mesh with said rack and connected tosaid transducer means.
 6. In a press according to claim 4 wherein saidselector means includes a series of limit switches arranged in a spacedlinear relationship with respect to the direction of travel of said ramadapted to be sequentially engaged by said ram during its workingstroke, said speed switch being associated with said limit switchadapted to be first engaged by said ram during its working stroke sothat when engaged said speed switch is operative.
 7. In a pressaccording to claim 4 wherein said first piston cylinder assemblycomprises a main piston cylinder assembly and said second pistoncylinder assembly comprising one or more auxiliary piston cylinderassemblies, means for associating a first limit switch in a manner toeffect operation of said main and auxiliary pisTon cylinder assembliesby said low pressure, means for associating a second limit switch withsaid high pressure system in a manner to effect operation of saidauxiliary piston cylinder assemblies by said high pressure, and meansfor associating a third limit switch with said high pressure system in amanner to effect said operation of a main piston cylinder assembly bysaid high pressure.